i have 2 textures, how can i turn one the textures on and off?
One simple method is to add a Maths 'Add' node between your texture and the color ramp. This allows you in set an offset to the texture to raise or lower it so it's more towards one texture or the other - ie, negative values will be more one texture, 0.0 will be an even mix, positive values will be more of the other texture (with larger values pushing the mix more in that direction).